Control of fuel injection mechanism for internal combustion engines



March 22, 1932.

E. VON SALIS CONTROL OF FUEL INJECTION MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Aug. 3, .1929

'INJQJTDF ,q-rn NEM Patented Mar. 22, 1932 UNITED STATES PATENT OFFICE EDUAED V0! ELLIS, OI WINTEBTHUB, SWITZERLAND, ASSIGNOB TO THE FIRM SULZEB FBEBES *SOCIETE' ANONYIE, OF WINTEBTHUR, SWITZERLAND CONTROL OF INJECTION MECHANISM FOR INTERNAL COMBUSTION ENGINES Application filed August 8, 1928, Serial llo. 888,306, and in Switzerland August 11, 192 8.

This invention relates to-an improvement in or modification of the invention claimed in the present applicants prior specification, now United States Patent 1,701,089, which relates to apparatus for controlling the fuel sure is removed from the fuel in the supply pipe. Experience has proved that such nonreturn or check valves do not always work in a perfectly reliable manner at the pressure involved, which lIl' tl'18 case of these engines amounted to several hundred atmospheres, and the object of the invention is to obviate the disadvantages which result.

According to this invention a throttle valve is substituted for the check or non-return valve in the branch pipe between the accumulator and the fuel injection device. It is true that the employment of such a valve results in a small quantity of fuel returning to the fuel supply pipe, but the quantity is so small and the time in which return flow can take place is so short, that for practical purposes it is negligible and in any event it is counteracted by correspondingly increasing the output of the fuel pump.

One construction according to this invention is diagrammatically illustrated by way of example in the accompanying drawing.

In the construction illustrated, fuel is supplied by the pump a to the housing or casing 6 of the fuel injection valve whichmay be mounted in the head of the internal combustion engine (not shown). The injection of fuel takes place in the usual manner when the engine piston is in the desired position in its stroke. The injection device in the example illustrated comprises a needle valve 0 having a surface (1 which forms a piston against which the pressure of the fuel accumulated'within the casing acts to lift the valve when this valve is released, thus perinitting fuel to be injected through the openvalve. Liquid fuel is, directly delivered to the piston m through a fuel supply pipe h from the pump a and the accumulator is connected through a throttle controlled opening I: to the fuel supply pi e. The pump is provided, in addition to the suction valve 1), with a check valve 0 which is opened by a control gear, not illustrated, as soon as in ection has to begin, that is, only during the pressure stroke of pump a. During the delivery stroke of the pump a charge of fuel passes into the accumulator throu h the throttle opening is and simultaneous y pressure is exerted upon the locking piston m of the needle valve. Against the action of the spring f the charge of fuel lifts the annular piston e away from the needle valve 0, but the needle valve remains closed under the action of the locking piston m. When the fuel is to be admitted into the working cylinder of the en e, pressure normally maintaining the nee le valve 0 on its seating is released by 0 ening the valve 0 in the pump pressure chamber thus reducing or neutral- 1 izing the pressure in the cylinder m so enabling the accumulated fuel to lift the needle valve 0 which will be raised by the action of the fuel, held back by the throttle valve at k and maintained under pressure by the annular piston. Valve 0 is opened only during the pressure stroke of the pump a. The annular piston will descend simultaneously with the injection of fuel into the engine cylinder and will thus positively force out and discharge the fuel in the accumulator through opening g, and return the needle 109 valve to its closed position by which means the injecting operation is brought to an end.

The throttle controlled opening is it is true allows some fuel to return intothe pipe 7 h but the quantity which thus returns is so small owing to the short time during which the valve is ,open that it can be ignored or it can be counteracted by correspondingly increasing the output of the pump. Owing to the accumulator being connected to the .fuel supply pipe through a throttle controlled opening instead of a non-return valve as hitherto, the whole operation of locking the injecting device, accumulating the fuel and actually injecting the fuel can be controlled from a distance by the use of a single movable control member and in this way the operation of the engine can be rendered more reliable.

It will be understood that some other form of accumulator may be employed and that other constructional details may be varied without departing from this invention.

I claim:

1. A liquid-fuel injecting system, comprising an injection valve having an accumulator-piston therearound, a compression mem ber tending to hold the accumulator-piston against rising, a source of fuel under pres sure, means for supplying fuel from said source to one end of said injection valve to normally maintain it closed, means for supplying fuel from said source to the other end of the valve, means for reducing the pressure of the fuel supplied to the first named end of the valve to cause the valve to rise and to permit the accumulator-piston to be forced down by the compression member, and means in the supply means to the second named valve end for reducing the cross-sectional area thereof and thus restricting the return flow of fuel therethrough during reduction in pressure on the first named end.

2. A liquid-fuel injection system, comprising an injection valve having an accumulator-piston therearound, a compression member tending to hold the accumulator-piston against rising, a source of fuel under pressure, means for supplying fuel from said source to one end of said injection valve to against rising a source of fuel under pressure, means for supplying fuel from said source to one end of said mjection valve to normally maintain it closed, means for supplying fuel from said source to the other end of the valve, means for reducing the pressure of the fuel supplied to the first named end of the valve to cause the valve to rise and to permit the accumulator-piston to be forced down by the compression member, and a throttle-valve in the supply pipe leading to to said second named end operable to maintain substantially constant, during the reduction of pressure on the first end, the pressure acting on said second named end.

In testimony whereof I have aflixed my signature.

EDUARD voN SALIS.

normally maintain it closed, means for supplying fuel from said source to the other end of the valve, means for reducing the pressure of the fuel supplied to the first named end of the valve to cause the valve to rise and to permit the accumulator-piston to be forced down by the compression member, and means for throttling the fuel tending to flow away from said second end when the pressure on the first end is reduced, to thereby maintain substantially constant thepressure acting on said second named end.

3. A liquid-fuel injection system, comprising an injection valve havingan accumulator-piston therearound, a compression member tending to hold the accumulator-piston 

